Table stop and reversing mechanism for grinding machines



NOV. 10, 1942. J GRUENBERG 2,301,621

TABLE STOP AND REVERSING MECHANISM FOR GRINDING MACHINES Filed March 3, 1941 INVENTOR IVOR J.GRUENBERG 51%: M WM ATTORNEYS Patented Nov. 10, 1942 "TABLE STOP AND REVE'RSING MECHANISM FOR GRINDING .MACHINES Ivor J. :Gruenberg, Ferndale, ;Mich., assignor to The Gear Grinding Machine Company, Hamtramck, Mich, a corporation of Michigan ApnlicationfiMarch 3, 19.41, Serial No. 3813574 3 .Claims.

In the manufacture of machin :parts that are to 'be subjected to relatively high istressespsmooth surface finish is becoming of increasing importance. This is for the reason that even a slight scratch or depression may serve to concentrate stresses at this point'whichmay eventually result n failure. In the earlier practice, it was customary to finish by grinding only those portions of the surface which were to contact orcooperate with other mechanical elements, leaving other portions in the rough. "This is no longer desirable, particularly where the weight factor is important, and consequently the part is reduced in dimensions so that the stresses 'the-rein'are relatively high. i

The invention relates more particularly to the finishing by grinding, after hardening through heat treatment, of mechanical "elements first fashioned by machining. For instance, spline members are generally first fashioned-by milling of spaced grooves 'in'the stock 'to form therebetween thesp'lines. Where :the slots or grooves do not extend the full length of the-member, forming what is generally known as blind splines, the ends of the slots will be curved to correspond to the circumference of the milling cutter, but these portions will not directly contact with the 'cooperating member engaging the splines. Consequently, in grinding the spline member to size after hardening, it was formerly the practice 'to finish only the full section portions of the spline. However, as-above stated/it is now considered desirable to finish all portions of the surface 'includingthe curvedend'portions of the slots. This not only requires that the grinder wheel should correspond in curvature to the milling cutter, but also that provision should be madefor stopping the work carrying table in its reciprocatory movement at an exact point. Otherwise, the

grinder wheel'might forced into thesolid stock at the end of a slot, which would "be highly 'detr imental.

It is the object of the invention to obtain a construction of table stop and reversing mechanism which is applicable to a hydraulic operating mechanism for reciprocating the table or carriage. To this end, the invention consists in the construction as hereinafter set forth.

In the drawing:

Fig. 1 is a diagrammatic view illustrating the operation of grinding a spline shaft, controlled by my improved mechanism;

Fig. 2 is an elevation of the table stop and reversing mechanism; and

In general, the .grinding machine is similar to constructions heretofore used, including a reciproca'tory work table VA, a mounting for the work thereon such as a spline shaft .3, which is :supported on centers C and is intermittently rotatably adjusted by an indexing mechanism (not shown) housed'within a casing D. The grinder wheel "E is mounted .on a suitable support (not shown), which permits of adjusting thezsame'into operative relation 'to the work. I shows diagrammatically a hydraulic motor for reciprocating the table, and G is a reversing valve which alternately directs the "fluid to the opposite ends of said motor to reciprocate the table A.

My improved stop and reversing mechanism includes a member H whichis mounted on the side of the table, being preferably adjus'tably secured by clamping screws "I, to the bar I on which the reversing dogs are usually-mounted. This member "has a depending lug H having an inclined surface H and a second lug H depends from the member H at a point spaced from the lug H. J' is a screw engaging a threaded aperture in the lug H having a milled head J at one end for adjusting the same, and an opposite end portion 'projectingjbeyond the lug. 'K is the bed of the machine on which the table H travels, and K is a housing secured to this bed which encloses a reversing valve-G. The specific construction of the reversing valve is not important, and

I have therefore merely shown a 'lever K projecting upward through a slot in the casing H which, when rocked in opposite directions, will function to reverse the valve. This lever extends into the path or the inclined portion or cam H on the lug .H' and also in the path of the projecting portion of'the screw J Thus, when the table is traveling in one direction, the screw J contacting with the lever K will move it to a position where the valve G is reversed, so that the hydraulic motor F Will return the table in the opposite direction. 'In the same manner, the-contacting'of the cam portion H with the lever K during the return movement of the table will rock the lever oppositely and again reverse the valve G, thereby starting the table once more in its forward direction.

As above stated, it is very important that the table should be stopped at an exact point in its forward movement where the grinder wheel comes in contact with the curved end portion B of the slots B which form the splines. This is accomplished by adjusting the screw J in the lug H so as to change its time of contact with Fig. 3 is a cross section on line 3-3 of Fig. 2. 55 the lever with respect to the movement of the occurs.

and the inertial force low at this point, it will table. However, this alone would not insure Stopping at an exact point. Slight variations in the viscosity of the oil operating the motor F, as well as the inertia of the moving table might cause it to move slightly farther one time then another before reversing its direction. I therefore have provided a stop mechanism which may be set to exactly correspond to a point in the movement of the table at which the grinder wheel contacts with the curved end of a slot. Such stop mechanism includes a hardened pad L at the forward end of the lug H, preferably the head of a screw engaging a threaded aperture in said lug. Also, a bumper M, which is adjustably secured to a member N mounted on the base K, has a hardened head and a screw threaded shank M which engages a corresponding threaded socket N in the member ML The shank may be rotatably adjusted by turning a milled head M and the amount of adjustment accurately indicated on an annular scale M The threaded socket N is split on one side, and screws N passing through the slotted portion serve to clamp the socket upon the threaded shank,

thereby holding it from accidental displacement.

With the construction as described, the bumper or stop M may be first adjusted through the turning of the head M so that the pad L contacts therewith when the grinder wheel comes into grinding contact with the curved end B of the slotin the splined shaft. The screw J may then be adjusted to a position where the table, when actuated by its hydraulic mechanism, will reverse before the pad L strikes the bumper M;

After this, during the continued reciprocation of the table, the screw J may be adjusted until the pad L contacts with the bumper before reversing As, the velocity of movement is slight not produce an'objectionable impact, but nevertheless the bumper will insure stopping at an exact point. a

What I claim as my invention is:

1. In a machine for grinding splines having intermediate' milled slots terminating in curved 1 blind ends, the combination witha reciprocatory same whenthe periphery of said grinder wheel contacts with the curved milled end of a slot, a member on said carriage for reversing said valve, and means'for adjusting said member to correspond to the setting of said stop.

2. In a machine for grinding splines having intermediate milled slots terminating in curved blind ends, ;the combination with a bed, a reciprocatory carriage mounted thereon for supporting the work, a hydraulic motor for actuating the same, and a reversing valve for controlling said motor provided with an upwardly extending rockable actuating member, of a grinder wheel formed to finish the sides of the splines on opposite sides of a milled slot, said grinder Wheel having its peripheral edge of a radius substantially corresponding to that of the curved ends of the milled slots, a mounting for the splined member upon said carriage, a bracket member adjustably mounted on said carriage to be positioned approximately in correspondence with the mounting of said splined member, a bumper pad secured to one end of said bracket membena stop mounted on said bed in the path of said pad to arrest movement of said carriage, a micrometer adjustment for said stop to set the same for arresting movement of said carriage at theexact point where the periphery of said grinder wheel forms grinding contact with the curved blind end of said slot, and a member for engaging said rockable member to operate said reversing valve, the said member having a screw thread engagement with said bracket member in spaced relation to said pad'and being adjustable I extending rockable actuating-member; of a grind- I enwheel formed to finish the sides of the splines on; opposite sides of a milled slot and also at-the bottom-of said slot, said grinder wheel having its peripheral portion of a radius substantially equal to the radius of curvature of the blind end of said slot, a mounting for the work: on said carriage, a bar extending longitudinally of said carriage on one side thereof, a bracketmember adjustably secured to said bar to be set approximately in correspondence with the work on said table, a bumper pad at oneendof said bracket member, a member mounted on said bed, a stop carried by said memberfor engaging said pad to arrest movement of said carriage, a micrometer adjustment for saidstop toset the same for arresting movement -of the carriage exactly at the point where the periphery of said grinder wheel forms grinding contact with the curved blind end of said slot, a screw engaging a threaded bearing. on said bracket member in spaced relation to said pad and adapted to engage said rockable member to efiect a reversing of said valve, said screw being adjustable to set the reversing of the valve in correspondence with the adjustment of said stop.

IVOR J. GRUENBERG. 

